We found this circuit in a 1956 Sylvania publication. It serves to monitor telegraph transmissions being placed next to the transmitter. The circuit is indicated for the range of 80 and 160 meters.
A low frequency or audio frequency generator is an almost indispensable instrument in which it...
This interesting radio circuit for listening on a crystal phone was found in a Japanese magazine in...
We found this circuit in an old American documentation. The operational amplifier is not common...